US Secretary of State Hillary Rodham Clinton on Wednesday encouraged Nigeria to tackle corruption and improve governance on the fifth leg of her Africa tour, according to dpa. "We strongly support and encourage the government of Nigeria's efforts to increase transparency, reduce corruption (and) provide support for democratic processes in preparation for the 2011 elections," Clinton said at a news conference in Abuja with Nigerian Foreign Minister Ojo Maduekwe. Despite the fact Nigeria is the US's fifth-largest supplier of oil, Clinton is believed to have delivered a stronger message behind the scenes to the government of what US officials call "the most important country in sub-Saharan Africa." She met with President Umaru Yar'Adua behind closed doors later in the day to hammer the message home. Nigeria is considered one of Africa's most corrupt states, with graft permeating every level of politics, business and society.